It seems you fail to distinguish between spin and "spin." Forget the ordinary English word "spin". And for clarity's sake just for you in this post let's call the other spxn. Let's suppose what is actually the case, that certain people use the term that we call here spxn to represent a set of ideas that they have collectively, and that they can convey to each other by speaking and writing the word spxn. In as much as I am not one of those people, I will leave to them the choice of their own words for their own use; and I (shall) assume the the word is efficacious when used by them among themselves. So much for the word — tim wood

It's not quite correct to ask for such a separation in the use of "spin", because no matter how you look at it spin is still a type of angular momentum, and this is a vector concept. The point I was making is that such dimensional concepts are not adequate for explaining the properties of particles which are assumed to be non-dimensional. Read the following from Wikipedia:

The three-dimensional angular momentum for a point particle is classically represented as a pseudovector r × p, the cross product of the particle's position vector r (relative to some origin) and its momentum vector; the latter is p = mv in Newtonian mechanics. Unlike linear momentum, angular momentum depends on where this origin is chosen, since the particle's position is measured from it. — Wikipedia: Angular momentum

Notice, "pseudovector", because the principles of classical 3-d vectors do not hold for these particles. So consider Flannel Jesus' explanation. The existence of the particle cannot be validated during the entire time between t1 and t100. It is only validated at these two time points through measurement of those properties like "spin". However, these concepts which make up those supposed properties are not adequate to measure what is really there at that time. So, since the existence of the particle is only known by determining these properties, at those two times, and these properties do not even accurately represent what is there at those times, and the indication is that there is no determinable particle between those times, then why should we even think that there is any particle at any time whatsoever? These dimensional concept like "spin" are misleading us.

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Bell’s theorem reveals that the entanglement-based correlations predicted by quantum mechanics are strikingly different from the sort of locally explicable correlations familiar in a classical context. — flannel jesus

I understand that phenomena at atomic and subatomic scales behave differently than those at human scale. It is common that phenomena at different scales behave differently. Superconductivity manifests at temperatures near absolute zero but is not seen at room temperature. Relativistic effects manifest at speeds near the speed of light but are not seen at slower speeds. What's the big deal?

"Validated"? I'm not sure this will be a useful discussion. It seems you want to commit the fallacy of, "Because I do not know, I know."

And if you were honest about it, you'd have taken note of the quoted remark above that make clear that the term - and the concepts - of spin are problematic, — tim wood

No, I'm being honest, it's not a matter of "because I do not know...". I'm going by what flannel jesus said:

Then, Bohr, Planck, Heisenberg, Schrodinger and friends introduced QM to the world. They said that there are some properties of particles that, prior to measurement, we can't actually tell a Classical story about. If we shoot a particle at t=0, through a double slit for example, and measure where that particle landed at t=100, we might be tempted to ask the question "ok, so where was that particle at t=50?" If the world worked classically, then there would be an objectively true answer to that question - even if we as human beings couldn't find an answer. If we can't find an answer, that's just our own ignorance, but there still *is* an answer. QM said, actually, there *is not* an answer. Or at least, not a *singular, definite answer* -- that's the phrasing I like to use. Prior to measurement, some of these properties of things like Photons and Electrons do not in fact have singular definite answers - not even to God. If God himself were to peer into the universe and look at that particle at t=50, he wouldn't have a singular definite answer to the question "where was that particle?" (Please note that I'm using God as a narrative tool, I'm not a theist. "God" is just a stand in for the idea of some external entity who could, in principle, know the world as it really is - could answer any question about any system without disturbing that system). — flannel jesus

If the particle has no location at t50, then there is no particle at that time. Why is that not obvious to you tim?. There is no such thing as an object like a particle, without a spatial location. To accept otherwise is to venture into a world filled with magic.

The detectors reliably and consistently measure something, called in this case spin - and it is at the moment irrelevant as to what spin is - and this spin deemed to be an aspect or quality of the particle itself. — tim wood

Let's be more precise with our terminology, let's just say that the detectors detect something. Because there is uncertainty between the relation of position and momentum, we ought not even call this a "measurement". Due to the uncertainty relation, we cannot accurately say what is being measured, so it's a stretch to even say it is a measurement.

And, because of this uncertainty, the concept referred to by "spin" is not a property of anything at all. It's just a mathematical way of describing what the detector detected. So if we go ahead and look at your proposition 'This spin is an aspect or quality of the particle itself', we must designate it as a false and misleading proposition. The detector is not really detecting any properties of any particles. It is detecting something which is called "spin", but the concept associated with this term in no way is an accurate representation of what is actually being detected

Denial of the particle having this spin except when it is measured begs the question as to how the particle knows it's being measured and reacts, and what, exactly, triggers that knowledge and reaction, not to speak of the time that all takes. — tim wood

Failure to recognize that there is not even a particle being detected, and that these dimensional-based (classical-based) concepts such as "spin" are woefully inadequate for describing the wave activity being detected, is misleading you here. I am not denying that the particle has "spin", I am denying that there is a particle. The concept, "spin", which refers to what is detected, does not properly represent what is actually detected, therefore the existence of the thing (particle) which is assumed to have that property is not substantiated (if you do not like "validated").

What's the big deal? Well, some dudes won the Nobel prize in 2022 in large part because of their experiments confirming violation of bells inequality, so the scientific establishment at large seems to understand that it's a big deal. I think it's pretty clear that the big deal is, violations of bells inequalities are unreproducible using classical means, and I believe that's what the Stanford quote is saying. I think it's a pretty big deal. You are of course under no obligation to think it's a big deal. You're under no obligation to be interested in QM at all. I, personally, think it's fascinating, mind blowing even.

Here's some other people across the internet who are apparently understanding it in similar ways to me:

https://physics.stackexchange.com/questions/732672/any-bell-experiments-showing-inequality-violations-in-purely-classical-systems-a

https://www.quora.com/In-simple-layman-s-terms-what-does-it-mean-to-violate-Bells-inequality-In-experiments-that-are-actually-done-how-is-the-violation-detected#:~:text=Short%20answer%3A,repetitions%20of%20a%20simple%20experiment.

(On the above link, see the second answer by amit)

https://physics.stackexchange.com/questions/370386/is-bells-inequality-always-violated

https://physics.stackexchange.com/questions/139880/can-bells-inequality-violation-be-explained-by-the-will-of-the-scientist-someho

https://physics.stackexchange.com/questions/675344/what-is-it-about-quantum-entanglement-that-cannot-be-explained-classically?noredirect=1&lq=1

Of course, all of these links do not prove I am correct. I'm not trying to prove I'm correct. I am trying to give you some signals that this isn't just some silly misunderstanding of bells theorem that I've invented. You may disagree that it is the correct way to understand bells Theorem, but I'm not pulling this understanding out of no where. I'm not just some silly goober inventing new nonsensical ways of understanding experiments. I believe my understanding is in fact the intended understanding.

What's the big deal?... I'm not just some silly goober inventing new nonsensical ways of understanding experiments. I believe my understanding is in fact the intended understanding. — flannel jesus

You have misrepresented the things I wrote in every response you've made to my posts in this discussion and I'm tired of it. What I'm saying is not that hard to understand and it doesn't contradict Bell's theorem or call into question the results of experimental testing or it's scientific importance.

I'm all done.

It was never my intention to deliberately misunderstand anything you wrote. The only misunderstanding you've explicitly pointed out so far is that bit about Many Worlds. If you don't want to explicitly lay out the things you think I'm misunderstanding, then of course I cannot correct my misunderstanding.

I don't even know what you mean about how what you're saying doesn't contradict bells theorem. As far as I can tell, this whole conversation lately has just been you telling me I'm misinterpreting bells theorem. I've never said your ideas contradict bells theorem, because I don't even know what your ideas are.

But if you're done, then see ya I guess.

this whole conversation lately has just been you telling me I'm misinterpreting bells theorem. — flannel jesus

I never said you misinterpreted Bell's theorem, I said you misrepresented what I wrote. Which you've just done again. I don't think our misunderstanding each other is intentional. It certainly isn't on my side.

Let's try this discussion again the next time it comes around. We're not getting anywhere here.

After I gave my understanding of bells theorem, your initial response was this:

In my understanding, this is not true. It is your interpretation, not mine and probably not Bell's. The inequalities are not "there to help us," they describe phenomena at very small scales.

And ever since that post, it's been me trying to defend what I've said about bells theorem. If that response you gave isn't you saying I've misinterpreted bells theorem, what is it? What else could it possibly be?

It's okay for you to think I've misinterpreted it. I'm here to talk about ideas, I'm not afraid of disagreement. I'm clearly willing to put in some energy and work to try to understand things properly, and defend my understanding when I think I've got it right.

I really just don't understand why your interactions with me are going in this direction. You said early in the thread that you've tried to understand what bells theorem is about. I made a post explaining what bells theorem is about. Then, somehow you went from not knowing what bells theorem is about to being incredibly confident that it's not about what I said, and you're confident bell himself would probably disagree.

But that's okay, you can disagree with me, I'm not throwing a temper tantrum about it, I'm communicating why I think what I think and defending my understanding. I'm not being aggressive towards you. I'm just trying to talk. If you don't want to talk about it you don't have to, but your role in this conversation has been quite strange and confusing from my perspective. I can't get a read on you at all. There's an air of hostility and I have no idea where it came from. And I can't understand why you're now saying you never said I misunderstood bells theorem. I'm so confused

I'm just trying to chat about this topic that I've spent a lot of energy over the past years understanding, because you said you didn't understand.

I actually have the words from Bell himself, this is the opening paragraph of his very own paper on his very own theorem (I'm having trouble getting a link on mobile, but it's easy enough to Google, just search BELLS THEOREM PAPER)

THE paradox of Einstein, Podolsky and Rosen [1] was advanced as an argument that quantum mechanics
could not be a complete theory but should be supplemented by additional variables. These additional vari-
ables were to restore to the theory causality and locality [2]. In this note that idea will be formulated
mathematically and shown to be incompatible with the statistical predictions of quantum mechanics. It is
the requirement of locality, or more precisely that the result of a measurement on one system be unaffected
by operations on a distant system with which it has interacted in the past, that creates the essential dif-
ficulty .

I believe the picture painted here by Bell himself is remarkably similar to the picture I painted of bells theorem. I painted a picture of bells theorem being about settling the difference between QM and the EPR paper, and that first statement by Bell is that this paper is going to be about that disagreement. I keep saying that it's about certain predictions of QM being incompatible with classical mechanics, and though he doesn't use the word "classical mechanics" here, he uses instead the phrase "causality and locality" - and I think it ought to be clear the relationship between that phrase and "classical mechanics" - and then says in the next sentence that that's incompatible with the predictions of quantum mechanics.

I do think that my interpretation of bells theorem is very much something Bell himself would agree with. I think I'm only barely using slightly different wording. I think I've pretty much got it. (In fact, I would argue my wording is less extreme than Bells)

The scientific side of all the Bell stuff comes in 2 parts. Part 1 is bells paper, where he argues that QM and "locality and causality" (which I'm calling classical mechanics) give irreconcilably different predictions, and then part 2 is the actual physical experiments done to confirm which of the two predictions bears out in reality, for which the nobel prize in physics in 2022 was awarded, which confirmed that we see the predictions of QM bear out.

I started my participation in this thread because I thought I could shed some light on a topic you said you didn't understand but wanted to. If you still want to, I think I've got plenty of good evidence that the understanding I have on offer is at least in the right direction. I won't quote you again though if you're done now, I just felt the need to defend my understanding given what you said about it.

I'm going to take a minute to just ramble and muse, if that's okay. I've given an explanation of what I think Bells Theorem is about, and in a nutshell it's simply that the universe doesn't work on classical causality.

I want to clarify something - that doesn't mean it doesn't operate on causality. I believe the universe DOES in fact operate on causality, just not classical causality.

I believe that bells theorem proves that you can't say "the particle was at this specific location at time t=50", and other such classical statements about the particle at moments when it's not being measured, BUT that doesn't mean I don't think you can say anything about the particle at t=50. I think you CAN say things, objectively true things, about the particle at t=50, just not most classical things.

I said above in my response to t.clark that my wording of the implication of bells theorem is actually less extreme than bells, because bell says QM is incompatible with local casualty - I'm only saying it's incompatible with Classical local causality.

None of what I'm saying should be taken to mean things cannot be casual, or things happen for no reason. They simply mean things aren't Classically casual, and they don't happen for Classical reasons.

I have been steering clear of a specific QM interpretation, because I didn't think it would help clarify anything, but I'm starting to think that both you and t.clark might benefit from me telling you unambiguously what I think in that regard, so here it is:

I believe Many Worlds is in fact the most likely reality. Many worlds is casual (locally, I think, though some people argue it's not local) - but it is not CLASSICALLY casual. In many worlds, things happen for "reasons", deterministically, just not CLASSICAL reasons. In many worlds, you can say things about a particle at t=50, you just can't say CLASSICAL things about that particle.

The sorts of things you can say about a particle at t=50 aren't "it was at this specific location going at this velocity", instead you can say things somewhat like "the wave function of the particles position at t=50 looks a bit like this, a cloud with dense regions here and here and less dense regions here, here, here and here." These are the sorts of objective statements you can make in a quantum world about unmeasured objects. This is what I meant when I said you have to bend your mind to accept different answers to the ones you're used to expecting. Most people expect the particle to have a specific location, and not to have an amplitude distribution.

I think many worlds is the most likely reality, but I'm not super confident of it. If it's not many worlds, the most likely alternative I think is that qm operates on some level of genuine randomness with non local causality, but I think that's pretty unlikely.

I hope that sheds some light on what you're trying to touch on with your "no reason" questions, Tim - I don't believe quantum things happen for "no reason", and I don't believe the things I've said necessarily imply that.

But at the end of the day, my goal here was not to talk much about what I believe about qm, but just about what Bells Theorem is fundamentally about. I think it's just about proving that QMs predictions are incompatible with classical physics. I believe the experiments that won the Nobel prize in 2022 demonstrate sufficiently that the physics of our universe at the scale of protons and photons etc are not classical.

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It seems to on any macro-scale. — tim wood

Yes, and the standard idea there is that macro level classical behaviours are emergent from micro level quantum behaviours

I would appreciate an excellent sentence or two on just what many-worlds is and entails. I understand it as a theory that says when you have to decide between apple and blueberry pie, the universe instantly divides into four separate and distinct universes where in each respectively you have either one or the other or both or neither. And this bifurcation occurring for every thing at every moment. But this is nonsense. How does it really work? — tim wood

First of all let me say that I don't want to derail this thread about Bells Theorem to be about many worlds. I'll try to briefly answer your questions, but it's not my intention to convince you of many worlds or defend it in any way. That being said...

At the center of many worlds is not humans, so centering the discussion on human decisions is not really advisable. Imo the idea that many worlds means anything you can imagine doing, there's some world where you do it is a misunderstanding. There may be some actual proponents of many worlds who agree, but I do not.

Many worlds is about the behaviour of fundamental particles. The wave functions in QM give a probability distribution of what properties those particles have and where they might be. The "world splitting" happens in the context of that probability distribution. If a particle has 50% of being here and 50% of being there, well there are worlds where it's here and worlds where it's there.

If you imagine some scenario about pie, there's not necessarily any sequence of quantum probabilities where you choose pumpkin pie, regardless of your ability to imagine yourself doing that.

If you ask other people who prefer many worlds, they may disagree with me on that point. I'm just speaking for myself here.

May we also agree that the reason is in some sense real? Not the description of it, although that real in an irrelevant sense. Perhaps usually the reason is some force? But whatever, real? My point here, that you may have already adverted to, being that everything that is, is real and distinct at some level in some way. (And thus that a god might know it if s/he cared to look, a perfect God always already knowing it.) — tim wood

The wording here is too vague for my liking. God might know what if God cared to look?

The wave functions themselves a function of inadequate knowledge — tim wood

Not in my opinion, no. Happy to explain why if you care.

What leads me to this is the notion of the electron as a cloud. I buy that as a description, but if it really is a cloud, then, to my knowledge, no one has yet given an account for how the cloud works. — tim wood

People have given an account of that. It's called the Schrödinger equation and it's a fundamentally important equation to quantum physics. It governs how that cloud evolves over time.

Interestingly, even though the common interpretation of quantum mechanics (not many worlds) is indeterministic, this particular equation is itself deterministic. Which means that, in the common understanding, you have a deterministic function determining the probabilities, which are then selected from indeterministically.

In my understanding, this is not true. It is your interpretation, not mine and probably not Bell's. The inequalities are not "there to help us," they describe phenomena at very small scales. — T Clark

What we have here is a failure to communicate.

In my understanding, this is not true. It is your interpretation, not mine and probably not Bell's. The inequalities are not "there to help us," they describe phenomena at very small scales. — T Clark

This statement doesn't challenge Bell's theorem, it's implications, or your interpretation. It's my pedantic way of saying that science describes how the world works. It doesn't have any purpose, it's just a description.

Scientific papers are absolutely published for purposes.

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you're of course free to think many worlds is wrong headed, I'm not here to defend many worlds, I'm not qualified to defend many worlds. I was just trying to answer your questions in good faith, to humour your curiosity. Reject it as you like.

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you're still talking about "decisions", which sounds to me like human decisions. I've indicated that in my view, quantum mechanics is not about human decisions. I don't believe that every imaginable human decision is realized in some world.

my previous reply was possibly too short. I meant it as a serious reply but I'm concerned the brevity of it might come across as snark rather than serious, so let me go into detail.

Many scientific papers are published for purposes. I believe this particular paper (on the EPR paradox by John bell) was, like many, published in order to persuade people about an idea that author had. That's certainly the effect it had - it has persuaded many people of an idea.

Do you think it was published to persuade? If so, what do you think it was trying to persuade people of?

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quantum mechanics certainly RESULTS in human decisions, I'm not disputing that. I'm saying it isn't ABOUT human decisions. Quantum mechanics is mathematical equations, and there's no operator in those equations for a "human decision".

So human decisions result from quantum events, yes, but quantum events aren't generally about human decisions. Some quantum events, according to MWI, CAN occasional spawn branches of the universal wave function where one human decision happened in this branch and another human decision happened in that branch - that can happen, but it is not required to happen for every imaginable decision you think you might be able to take, in my opinion.

I don't speak for everyone who prefers MWI, though.

There's interpretations within interpretations. Agggh

Many scientific papers are published for purposes. — flannel jesus

I don't think there's much of a disagreement between you and me and what there is is metaphysical, epistemological, not scientific. You and I just seem to have trouble linking up. Let's leave it at that and I'll try harder in our next conversation.

sure, despite the misunderstanding I appreciate your participation and hope I run into you again in the future. Wish I could have expressed myself more clearly. Have a good one

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https://static.scientificamerican.com/sciam/assets/media/pdf/197911_0158.pdf — tim wood

I thought this was a really good article. I understand the subject now way more than I did, though I'm still trying to sort through it and the ramifications in my head. How did you find it, I guess you had a physical copy lying around?

To give an idea of the caliber of writer SA used to employ:
https://en.wikipedia.org/wiki/Bernard_d%27Espagnat


FWIW (probably nothing), my take on "quantum ontology" is that there is a kind of tolerancing to the universe. The universe is as exactly as specified as it needs to be, and no more. If something (a quantum state) may remain unspecified, it remains unspecified, and the range of possible states and their likelihoods exactly describe it. It is a bit analogous to "lazy evaluation" in software programming. I find this elegant and efficient, not spooky.

I don't know what any of that means, I'm sorry

I've appreciated your comments here, thanks for that. Frankly I feel like he is flailing without knowing what he is talking about.